It would require a heavy reworking of the now 11-country agreement, which has since been renamed the Comprehensive and Progressive Agreement for Trans-Pacific Partnership.

The absence of the US saw the investor-state dispute clauses in the agreement tightened and copyright extensions canned.

Despite the changes, prominent critic of the TPP Prof Jane Kelsey called it the "same old deal" with added tinsel, and she's found herself in unlikely agreement with National Party MP Judith Collins.

"The fact is, it's pretty much the same as what we signed up to," Ms Collins told The AM Show on Friday.

Judith Collins and Phil Twyford.
Photo credit: The AM Show

While talks on the TPP began under Helen Clark's Labour Government, National made it a priority and officially signed New Zealand up to an earlier version of it in early 2016.

She told Labour MP Phil Twyford, appearing with her on The AM Show, his defence of the new agreement was "spin" that made her want to vomit.

"You marched against it, you're in Government, all of a sudden, 'Oh gee, we need this for our exporters.' Come on Phil, just front up."

"It has changed, it has improved," said Mr Twyford. "I'm sorry to hear Judith Collins talking down this big opportunity for our exporters."

He said concerns over the investor-state dispute clause had been allayed by not letting companies sue the Government through overseas tribunals - requiring them to go through the New Zealand court system.

"The investor-state dispute provisions are still in there, but they have been constrained. They've been wound back - more than 80 percent of the parties who can use them have basically agreed not to."

Trade Minister David Parker told RNZ on Thursday the remaining risk of being taken to court was offset by the trade boosts the TPP will give exporters.